aspherics

Modern lenses boast about 7-elements or aspherics, but does that actually matter in prime lenses?

In general, a 3/5-element design (achromat/apochromat) should do the trick I think, provided you have access to arbitrary aspherics.

Also, as a practical matter, designers often use several spherical lenses instead of a few aspherics because the latter are harder to manufacture/more expensive.

Since I'm a nerd, I read up on lens materials and now I use Trivex single vision aspherics for readers and drivers.

I can highly recommend [0] for some reading on how simple optics can be if you can optimize aspherics for a fixed focus.

Good lenses are important - I was sceptical but I'm much happier with my Seiko 1.74 double aspheric than with my old glasses which were Specsaver's 1.74 aspherics: flatter front and less distortion and rainbow effects (chromatic aberration).